U.S. patent number 7,301,381 [Application Number 11/194,272] was granted by the patent office on 2007-11-27 for clocked state devices including master-slave terminal transmission gates and methods of operating same.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Sung-we Cho, Young-chul Rhee.
United States Patent |
7,301,381 |
Rhee , et al. |
November 27, 2007 |
Clocked state devices including master-slave terminal transmission
gates and methods of operating same
Abstract
A clocked state circuit can include a transmission gate
configured to clock an output of a master terminal to an input of a
slave terminal responsive to a clock signal or a delayed clock
signal coupled to the transmission gate.
Inventors: |
Rhee; Young-chul (Gyeonggi-do,
KR), Cho; Sung-we (Seoul, KR) |
Assignee: |
Samsung Electronics Co., Ltd.
(Gyeonggi-do, KR)
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Family
ID: |
36385642 |
Appl.
No.: |
11/194,272 |
Filed: |
August 1, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060103443 A1 |
May 18, 2006 |
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Foreign Application Priority Data
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Nov 17, 2004 [KR] |
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10-2004-0094176 |
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Current U.S.
Class: |
327/203; 327/212;
327/211; 327/218; 327/201 |
Current CPC
Class: |
H03K
3/35625 (20130101); H03K 3/0372 (20130101) |
Current International
Class: |
H03K
3/289 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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11-330917 |
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Nov 1999 |
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JP |
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2004-017948 |
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Mar 2004 |
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KR |
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Primary Examiner: Lam; Tuan T.
Assistant Examiner: Hernandez; William
Attorney, Agent or Firm: Myers, Bigel, Sibley & Sajovec,
P.A.
Claims
What is claimed:
1. A high-speed flip-flop comprising: a master terminal receiving
input data in response to an inverted clock signal and an internal
clock signal, the inverted clock signal being generated by
inverting a clock signal; a slave terminal receiving an output of
the master terminal and outputting the received output as an output
signal in response to the inverted clock signal and the internal
clock signal; and an output pre-driving unit driving the output
signal in response to the inverted clock signal and an output of
the master terminal, wherein the master terminal comprises: a first
inverter receiving a clock signal and outputting the inverted clock
signal; a second inverter receiving the inverted clock signal and
outputting the internal clock signal; a first tri-state buffer
receiving the input data in response to the internal clock signal
and the inverted clock signal; and a first latch latching an output
of the first tri-state buffer wherein the output pre-driving unit
comprises: a first PMOS transistor having a source to which a
supply voltage is applied, and a gate to which the inverted clock
signal is input; and a second PMOS transistor having a source
connected to a drain of the first PMOS transistor, a drain to which
the output signal is input, and a gate to which the output of the
master terminal is input.
2. The high-speed flip-flop of claim 1, wherein the first latch
comprises: a third inverter receiving the output of the first
tri-state buffer; a fourth inverter receiving an output of the
third inverter; and a first transmission gate transmitting an
output of the fourth inverter to the third inverter in response to
the inverted clock signal and the internal clock signal.
3. The high-speed flip-flop of claim 1, wherein the slave terminal
comprises: a second transmission gate transmitting an output of the
master terminal in response to the inverted clock signal and the
internal clock signal; a second latch latching an output of the
second transmission gate; and a fifth inverter receiving the output
of the second transmission gate and outputting the output
signal.
4. The high-speed flip-flop of claim 3, wherein the second latch
comprises: a sixth inverter receiving the output of the second
transmission gate; and a second tri-state buffer receiving an
output of the sixth inverter and feeding back the received output
to the sixth inverter in response to the internal clock signal and
the inverted clock signal.
5. A method of operating a clocked state circuit comprising:
clocking an output of a master terminal to an input of a slave
terminal responsive to a clock signal or a delayed clock signal
coupled to a transmission gate therebetween; driving an output
signal from an output pre-driving unit in response to an inverted
clock signal and the output of the master terminal, wherein the
master terminal comprises: a first inverter receiving an external
clock signal and outputting the clock signal; a second inverter
receiving the clock signal and outputting the delayed clock signal;
a first tri-state buffer receiving input data in response to the
clock signal and the delayed clock signal; and a first latch
latching an output of the first tri-state buffer wherein the output
pre-driving unit comprises: a first PMOS transistor having a source
to which a supply voltage is applied, and a gate to which the
inverted clock signal is input; and a second PMOS transistor having
a source connected to a drain of the first PMOS transistor, a drain
to which the output signal is input, and a gate to which the output
of the master terminal is input.
6. A method according to claim 5 further comprising transmitting
the output of the master terminal to the input of the slave
terminal responsive to a logical OR function of a first state of
the clock signal and a second state of the delayed clock signal,
wherein the second state is opposite the first state.
7. A method according to claim 5 wherein transmitting comprises:
transmitting the output of the master terminal to the input of the
slave terminal responsive to a first state of the clock signal; and
transmitting the output of the master terminal to the input of the
slave terminal responsive to a second state of the delayed clock
signal, wherein the second state is opposite the first state.
8. A high-speed flip-flop comprising: a first inverter receiving a
clock signal and outputting an inverted clock signal; a second
inverter receiving the inverted clock signal and an internal clock
signal; a first tri-state buffer receiving input data in response
to the internal clock signal and the inverted clock signal; a first
latch latching an output of the first tri-state buffer; a second
transmission gate transmitting an output of the first latch in
response to the inverted clock signal and the internal clock
signal; a second latch latching an output of the second
transmission gate; a fifth inverter receiving the output of the
second transmission gate and outputting an output signal; a first
PMOS transistor having a source to which a supply voltage is
applied, and a gate to which the inverted clock signal is input;
and a second PMOS transistor having a source connected to a drain
of the first PMOS transistor, a drain to which the output signal is
input, and a gate to which an output of the first latch is
input.
9. The high-speed flip-flop of claim 8, wherein the first latch
comprises: a third inverter receiving the output of the first
tri-state buffer; a fourth inverter receiving an output of the
third inverter; and a first transmission gate transmitting an
output of the fourth inverter to the third inverter in response to
the inverted clock signal and the internal clock signal.
10. The high-speed flip-flop of claim 8, wherein the second latch
comprises: a sixth inverter receiving the output of the second
transmission gate; and a second tri-state buffer receiving an
output of the sixth inverter and feeding back the received output
to the sixth inverter.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority of Korean Patent Application
No. 10-2004-0094176, filed on Nov. 17, 2004, in the Korean
Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
FIELD OF THE INVENTION
The present invention relates to integrated circuits, and more
particularly, to clocked state devices and methods of operating the
same.
BACKGROUND
A flip-flop is a general data storage device used in a digital
electronic circuit. The flip-flop can be a significant factor in
designing a digital electronic circuit, since it is a clocked
storage (or state) element used to design sequential and stable
logic. The flip-flop can be used to store logic states, parameters,
or digital control signals.
To realize a high-performance microprocessor, the flip-flop may be
manufactured to operate at maximum logic clocking speed while
reducing flip-flop setup/hold time and clock-to-output time. In
addition, the flip-flops should have a short data response time
while reducing data-to-clock time.
FIG. 1 is a circuit diagram of a conventional flip-flop 100. The
flip-flop 100 includes a master terminal 110 and a slave terminal
120 that use tri-state buffers as switching elements. The master
terminal 110 includes a first inverter 111 that receives a clock
signal CK and outputs an inverted clock signal CKB, a second
inverter 112 that receives the inverted clock signal CKB and
outputs an internal clock signal CKI, a first tri-state buffer 113
that receives input data D in response to the internal clock signal
CKI and the inverted clock signal CKB, and a first latch 114 that
latches an output of the first tri-state buffer 113. The first
latch 114 includes a third inverter 115 that receives the output of
the first tri-state buffer 113, and a second tri-state buffer 116
that receives an output of the third inverter 115 and feeds back
the received output to the third inverter 115 in response to the
inverted clock signal CKB and the internal clock signal CKI.
The slave terminal 120 includes a third tri-state buffer 121 that
receives an output of the first latch 114 in response to the
inverted clock signal CKB and the internal clock signal CKI, a
second latch 122 that latches an output of the third tri-state
buffer 121, and a fourth inverter 123 that receives the output of
the third tri-state buffer 121 and outputs an output signal Q. The
second latch 122 includes a fifth inverter 124 that receives the
output of the third tri-state buffer 121, and a fourth tri-state
buffer 125 that receives an output of the fifth inverter 124 and
feeds back the received output to the fifth inverter 124 to latch
the output in response to the internal clock signal CKI and the
inverted clock signal CKB.
FIG. 2 is a circuit diagram of a tri-state buffer, such as the
tri-state buffers 113, 116, 121, and 125. Referring to FIG. 2, the
tri-state buffer generates an output signal Y by inverting an input
signal A in response to a first enable signal CKP and a second
enable signal CKN. The tri-state buffer includes first and second
PMOS transistors 201 and 202 and first and second NMOS transistors
203 and 204, which are connected in series between a supply voltage
VDD and a ground voltage VSS. The input signal A is input to the
gates of the first PMOS transistor 201 and the second NMOS
transistor 204, the first enable signal CKP is input to the gate of
the second PMOS transistor 202, and the second enable signal CKN is
input to the gate of the first NMOS transistor 203. The logic
levels of first enable signal CKP and the second enable signal CKN
are different from each other (i.e., out of phase with one
another), like the inverted clock signal CKB and the internal clock
signal CKI illustrated in FIG. 1.
The flip-flop 100 stores the input data D in the master terminal
110 in response to the clock signal CK that goes to logic low, and
outputs the data D stored in the master terminal 110 as the output
signal Q to be output from the slave terminal 120 in response to
the clock signal CK that goes to logic high. In this case, the
tri-state buffers 113, 116, 121, and 125 of the flip-flop 100 are
selectively enabled in response to the inverted clock signal CKB
and the internal clock signal CKI. When the clock signal CK is
input to the master terminal 110, the inverted clock signal CKB and
the internal clock signal CKI are output from the first and second
inverters 111 and 112, respectively. Accordingly, a delay in the
operations of the first and second inverters 111 and 112 results
can provide a delay in generation of the inverted clock signal CKB
and the internal clock signal CKI. A delay in the generation of the
inverted cock signal CKB and the internal clock signal CKI may
reduce the operating speed of the flip-flop 100, which may affect
the operating speed of the flip-flop 100.
SUMMARY
Embodiments according to the invention can provide clocked state
devices including master-slave terminal transmission gate and
methods of operating the same. Pursuant to these embodiments, a
clocked state circuit can include a transmission gate configured to
clock an output of a master terminal to an input of a slave
terminal responsive to a clock signal or a delayed clock signal
coupled to the transmission gate. In some embodiments according to
the invention, the circuit further includes a first inverter
circuit including an input coupled to an external clock and an
output to provide the clock signal. A second inverter circuit
includes an input coupled to the clock signal and an output to
provide the delayed clock signal.
In some embodiments according to the invention, the transmission
gate is further configured to transmit the output of the master
terminal to the input of the slave terminal responsive a logical OR
function of a first state of the clock signal and a second state of
the delayed clock signal, wherein the second state is opposite the
first state. In some embodiments according to the invention, the
transmission gate includes a first pass transistor configured to
transmit the output of the master terminal to the input of the
slave terminal responsive to a first state of the clock signal. A
second pass transistor is configured to transmit the output of the
master terminal to the input of the slave terminal responsive to a
second state of the delayed clock signal, wherein the second state
is opposite the first state. In some embodiments according to the
invention, the first pass transistor is an NMOS transistor and the
second pass transistor is a PMOS transistor.
In some embodiments according to the invention, the circuit further
includes an output pre-driving circuit including an input coupled
to the output of the master terminal and an output coupled to an
output of the slave terminal, wherein the output pre-driving
circuit is configured to drive data provided at the output of the
master terminal to the an output of the slave terminal responsive
to a state of the clock signal.
In some embodiments according to the invention, the output
pre-driving circuit includes a data output gate including an input
coupled to the output of the master terminal and an output coupled
to the output of the slave terminal. A pull-up gate is coupled to
the data output gate and configured to pull up the output of the
data output gate responsive to a state of the clock signal.
In some embodiments according to the invention, the master terminal
further includes a tri-state inverter circuit coupled to a data
input of the clocked state circuit configured to provide inverted
data. A latch circuit is coupled to the inverted data and
configured to latch the inverted data to provide latched inverted
data to the transmission gate.
In some embodiments according to the invention, the latch circuit
is a first latch circuit and the slave terminal further includes a
second latch circuit coupled to the transmission gate and
configured to latch the output therefrom. An inverter circuit is
coupled to the transmission gate and configured to provide output
data to an output of the clocked state circuit.
In some embodiments according to the invention, the circuit further
includes an output pre-driving circuit including an input coupled
to the output of the master terminal and an output coupled to an
output of the slave terminal, wherein the output pre-driving
circuit is configured to drive data provided at the output of the
master terminal to the an output of the slave terminal responsive
to a state of the clock signal.
In some embodiments according to the invention, a method of
operating a clocked state circuit includes clocking an output of a
master terminal to an input of a slave terminal responsive to a
clock signal or a delayed clock signal coupled to a transmission
gate therebetween.
In some embodiments according to the invention, the method further
includes inverting an external clock to provide the clock signal
and inverting the clock signal to provide the delayed clock signal.
In some embodiments according to the invention, the method further
includes transmitting the output of the master terminal to the
input of the slave terminal responsive a logical OR function of a
first state of the clock signal and a second state of the delayed
clock signal, wherein the second state is opposite the first
state.
In some embodiments according to the invention, transmitting
includes transmitting the output of the master terminal to the
input of the slave terminal responsive to a first state of the
clock signal. The output of the master terminal is transmitted to
the input of the slave terminal responsive to a second state of the
delayed clock signal, wherein the second state is opposite the
first state.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a circuit diagram of a conventional flip-flop.
FIG. 2 is a circuit diagram of a conventional tri-state buffer.
FIG. 3 is a circuit diagram of a flip-flop according to some
embodiments of the present invention.
FIG. 4 is a graph comparatively illustrating delays in operations
of a flip-flop according to an exemplary embodiment the present
invention and a conventional flip-flop.
FIG. 5 is a graph comparatively illustrating power consumed by a
flip-flop according to an exemplary embodiment of the present
invention and a conventional flip-flop.
FIG. 6 is a graph illustrating the multiplication characteristics
of delays and power consumption of a flip-flop in some embodiments
according to the present invention.
DESCRIPTION OF EMBODIMENTS ACCORDING TO THE INVENTION
The invention is described more fully hereinafter with reference to
the accompanying figures, in which embodiments of the invention are
shown. This invention may, however, be embodied in many alternate
forms and should not be construed as limited to the embodiments set
forth herein.
Accordingly, while the invention is susceptible to various
modifications and alternative forms, specific embodiments thereof
are shown by way of example in the drawings and will herein be
described in detail. It should be understood, however, that there
is no intent to limit the invention to the particular forms
disclosed, but on the contrary, the invention is to cover all
modifications, equivalents, and alternatives falling within the
spirit and scope of the invention as defined by the claims. Like
numbers refer to like elements throughout the description of the
figures.
The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. As
used herein the term "and/or" includes any and all combinations of
one or more of the associated listed items.
It will be understood that, although the terms first, second, etc.
may be used herein to describe various elements, these elements
should not be limited by these terms. These terms are only used to
distinguish one element from another. For example, a first element
could be termed a second element, and, similarly, a second element
could be termed a first element without departing from the
teachings of the disclosure.
Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
FIG. 3 is a circuit diagram of a flip-flop 300 according to some
embodiments of the present invention. In some embodiments according
to the invention, the flip-flop 300 includes a master terminal 310
and a slave terminal 320 that use transmission gates as switching
elements, and an output pre-driving unit (or circuit) 330. The
master terminal 310 includes a first inverter (circuit) 311 that
receives a clock signal CK and outputs an inverted clock signal
CKB, a second inverter 312 that receives the inverted clock signal
CKB and outputs an internal clock signal CKI, a first tri-state
buffer 313 that receives input data D in response to the internal
clock signal CKI and the inverted clock signal CKB, and a first
latch 314 that latches an output of the first tri-state buffer 313.
The first latch 314 includes a third inverter 315 that receives the
output of the first tri-state buffer 313, a fourth buffer 316 that
receives an output of the third inverter 315, and a first
transmission gate 319 that transmits an output of the fourth buffer
316 to the third inverter 315 in response to the inverted clock
signal CKB and the internal clock signal CKI.
In some embodiments according to the invention, the slave terminal
320 includes a second transmission gate 321 that transmits an
output of the first latch 314 in response to the inverted clock
signal CKB and the internal clock signal CKI, a second latch 322
that latches an output of the second transmission gate 321, and a
fifth inverter 323 that receives an output of the second
transmission gate 321 and outputs an output signal Q. The second
latch 322 includes a sixth inverter 324 that receives the output of
the second transmission gate 321, and a second tri-state buffer 325
that receives an output of the sixth inverter 324 and feeds back
the received output to the sixth inverter 324 in response to the
internal clock signal CKI and the inverted clock signal CKB.
The output pre-driving unit 330 includes first and second PMOS
transistors 331 and 332 connected in series between a supply
voltage VDD and the output signal Q. The inverted clock signal CKB
is input to the gate of the first PMOS transistor 331, and the
output of the first latch 314 is input to the gate of the second
PMOS transistor 332.
In some embodiments according to the invention, the input data D is
output to the first latch 314 using the master terminal 310
operating in response to the clock signal that goes to logic low,
and then, an output of the first latch 314 is output as the output
signal Q using the slave terminal 320 operating in response to the
clock signal CK that goes to logic high or the output signal Q is
driven using the output pre-driving unit 330.
In some embodiments according to the invention, when the input data
D is at a logic high level, the inverted clock signal CKB and the
internal clock signal CKI generated by the master terminal 310 in
response to the clock signal CK that goes to logic low are at a
logic high level and a logic low level, respectively. Thus, both
the outputs of the first tri-state buffer 313 and the first latch
314 are at a logic low level. Next, the inverted clock signal CKB
goes to logic low and the internal clock signal CKI goes to logic
high, in response to the clock signal CK at a logic high level. In
the output pre-driving unit 330, the first PMOS transistor 331 is
turned on in response to the inverted clocks signal CKB at a logic
low level, the second PMOS transistor 332 is turned on in response
to the output of the first latch 314 at a logic low level, and the
output signal Q is output at a logic high level equal to the supply
voltage VDD. In this case, in the slave terminal 320, when the
second transmission gate 321 is turned on, the output of the first
latch 314 that goes logic low is input to the fifth inverter 323
and output, as the output signal Q that goes logic high, from the
fifth inverter 323. In other words, in some embodiments according
to the invention, the flip-fop 300 receives the input data D at a
logic high level and outputs the output signal Q at a logic high
level.
In some embodiments according to the invention, when the input data
D is at a logic low level, both the outputs of the first tri-state
buffer 313 and the first latch 314 are generated at a logic high
level in response to the inverted clock signal CKB at a logic high
level and the internal clock signal CKI at a logic low level. Next,
the inverted clock signal CKB is at a logic low level and an the
internal clock signal CKI is at a logic high level in response to
the clock signal that goes to logic high. In this case, the second
transmission gate 321 of the slave terminal 320 is turned on, and
the output of the first latch 314 that goes to logic high is input
to the fifth inverter 323 and output, as the output signal Q that
goes to logic low, from the fifth inverter 323. In this case, in
the output pre-driving unit 330, the second PMOS 332 is turned off
in response to the output of the first latch 314 at a logic high
level, and thus, supply of the supply voltage VDD is discontinued.
That is, the flip-flop 300 receives the input data D at a logic low
level and outputs the output signal Q at a logic low level.
In some embodiments according to the invention, the flip-flop 300
receives the input data D and generates the output signal Q in
response to the inverted clock signal CKB obtained by inverting the
clock signal CK using the first inverter 311. Thus, in some
embodiments according to the invention, it is possible to reduce a
delay in the operation of the flip-flop 300 as compared to when
generating the inverted clock signal CKB and the internal clock
signal CKI using the two inverters 111 and 112 of FIG. 1.
Accordingly, the flip-flop 300 may operate faster than the
conventional flip-flop 100 of FIG. 1.
FIGS. 4 through 6 are graphs comparing exemplary performance of a
flip-flop 300 according to an embodiment of the invention and the
conventional flip-flop 100. Specifically, FIG. 4 is a graph
illustrating delays in the operation of a flip-flop 300 and the
operation of the conventional flip-flop 100. Referring to FIG. 5, a
delay in the operation of the flip-flop 300 was reduced by 12 to
23% compared to that in the operation of the conventional flip-flop
100. FIG. 5 is a graph illustrating the amounts of power consumed
by the flip-flop 300 and the conventional flip-flop 100. Referring
to FIG. 5, the amount of power consumed by the flip-flop 300 was
lower by 8 to 17% than that of power consumed by the conventional
flip-flop 100. FIG. 6 is a graph comparing the multiplication
characteristics of delay and power consumption of the flip-flop 300
with those of delay and power consumption of the conventional
flip-flop 100. Referring to FIG. 6, the result of multiplication of
the flip-flop 300 was higher by 5 to 10% than that of
multiplication of the conventional flip-flop 100.
Although the present invention has been described with reference to
the embodiment thereof, it will be understood that the invention is
not limited to the details thereof. Various substitutions and
modifications have been suggested in the foregoing description, and
other will occur to those of ordinary skill in the art. Therefore,
all such substitutions and modifications are intended to be
embraced within the scope of the invention as defined in the
appended claims.
* * * * *